The noble metals
Are exemplified by Na, K and Li
Do not resist corrosion very strongly
Are the lowermost in the electro-chemical series of metals
None of these
Correct Answer :
C. Are the lowermost in the electro-chemical series of metals
Related Questions
Baffles provided on the shell side of a shell and tube heat exchanger are meant for
Providing support for the tubes
Improving heat transfer
Both 'a' & 'b'
Preventing the fouling of tubes & stagnation of shell side fluid
Material of construction of the electrode used in the electric resistance welding is
Stainless steel
Graphite
Copper
Steel
Which of the following is prone to cup and cone fracture?
Cast iron
Soft brass
Round specimen of ductile metal
Flat tensile specimen of ductile metal
While the oxy-acetylene flame produces a temperature of 3200°C, the temperature produced by oxy-hydrogen flame is about __________ °C.
1800
2000
2400
3000
Wohler test is a destructive test to find out the __________ strength of a prepared metal specimen.
Creep
Fatigue
Endurance
Tensile
The function of neutral flux used in the pyrometallurgy of metal extraction is to increase the __________ of the slag.
Fluidity
Basicity
Acidity
Viscosity
Half life of a radioactive isotope corresponds to the time required for half of the __________ to decay.
Atoms
Neutrons
Nucleons
Electrons
On being hit with a hammer, __________ will readily fracture.
Brass
Mild steel
Cast iron
Lead
The yield point phenomenon observed in annealed low carbon steel is due to the presence of the following element.
Silicon
Carbon
Phosphorous
Chromium
Super conduction in metals is observed at a temperature of __________ °K.
<100
>100
About 273
About 373
The bank of tubes located at the back of the domestic refrigerators are the __________ tubes.
Refrigerant cooling
Evaporator
Condenser
Throttling
Principal alloying element in Elinvar (used for making hair springs for watches) is
Copper
Aluminium
Nickel
Zinc
Maximum permissible air velocity in pipelines is about __________ metre/second.
5
10
20
40
In __________ process, there is an increase in entropy with no degradation of energy.
Isothermal expansion
Isochoric heat addition
Polytropic expansion
Isobaric heat addition
Dephosphorization of molten pig iron is favoured by
Oxidising and basic slag
Reducing and basic slag
High activity co-efficient of phosphorous in metal
Oxidising and neutral slag
Steel containing low percentage of nickel, chromium & tungsten are termed as the __________ steel.
Wrought
Tool
Alloy
Plain carbon
Heat transfer to the water wall in a high pressure water wall type boiler furnace is mainly by
Conduction
Convection
Radiation
Both 'a' & 'b'
__________ flux is used for the extraction of metal from its self fluxing ores.
No
Acid
Basic
Neutral
Thermal diffusivity of a substance is proportional to (where, k = Thermal conductivity)
1/k
k
k2
1/k2
Coating provided on the electrodes used in the arc welding is not expected to
Add alloying elements
Prevent electrode from contamination
Stabilise the arc
Provide protective atmosphere to weld
Hollow shafts can be made as strong as solid shafts by making the twisting moments of both the shafts same. Shafts made by __________ have residual stresses.
Forging
Cold rolling
Hot rolling
Casting
Which of the following hardness tests does not measure the indentation hardness of metals and alloys?
Vickers hardness test
Shore scleroscope test
Brinell hardness test
Rockwell hardness test
Case hardening is not done by
Nitriding
Hot dipping
Electroplating
Both b & c
For infinite parallel planes having emissivities ε1 & ε2, the interchange factor for radiation from surface 1 to surface 2 is given by
The excess air required for the combustion of pulverised coal is of the order of about __________ percent.
5
15
30
45
Vernier calipers cannot be used to measure the
I.D. & O.D. of the shaft
Thickness of parts
Depth of holes
Clearance between two mating surfaces
Latent heat of dry steam at atmospheric pressure is 539 Kcal/kg; which __________ with increase in the pressure of steam.
Decreases
Increases
Remain same
May increase or decrease
__________ is used for tying the steel columns to concrete foundation.
Grouting
Eyebolt
Anchor bolts
Refractory castables
Pick out the correct statement.
Hot worked materials are subjected to annealing to remove internal stresses
Annealing of steel hardens it slightly
Normalising of a material induces stresses
Tempering of a material improves ductility & toughness but reduces hardness & brittleness
Copper deposits are found in India at the following location:
Kudremukh
Kolar
Khetri
Ramagundam